Dental caries is a major public health problem around the world. Dental caries has been identified as the single most common chronic disease of childhood. Despite the strides made in treating and preventing dental caries, significantly more needs to be done to further tackle the problem.
Dental caries is a chronic infectious disease. Earlier detection would reduce the ravages of the disease; it allows dental professionals to administer professional treatments to reverse the caries process rather than undertake more costly and less desirable restorative treatments.
Traditional methods for caries detection include visual examination and tactile probing with a sharp dental explorer device, often assisted by radiographic (x-ray) imaging. There are risks associated with conventional detection techniques, including the risk of damaging weakened teeth, spreading infection and exposure to x-ray radiation.
In response to the need for improved caries detection methods, there has been interest in improved imaging techniques that do not employ x-rays. One method that has been commercialized employs fluorescence, caused when teeth are illuminated with high intensity UV-blue light. This technique, termed quantitative light-induced fluorescence (QLF), operates on the principle that sound, healthy tooth enamel yields a higher intensity of fluorescence under excitation from some wavelengths than does de-mineralized enamel that has been damaged by caries infection. The strong correlation between mineral loss and loss of fluorescence for UV-blue light excitation is then used to identify and assess carious areas of the tooth.
In U.S. patent application Ser. No. 11/468,883, a method and apparatus that employs both the reflectance and fluorescence images of the tooth is used to detect caries. It takes advantage of the observed back-scattering for incipient caries and in combination with fluorescence effects, to provide an improved dental imaging technique to detect caries. The technique, referred to as fluorescence imaging with reflectance enhancement (FIRE), helps to increase the contrast of images over that of earlier approaches, and also makes it possible to detect incipient caries at stages when preventive measures are likely to take effect. Advantageously, FIRE detection can be accurate at an earlier stage of caries infection than has been exhibited using existing fluorescence approaches that measure fluorescence alone. The Application describes a downshifting method (referred to as downshifting-FIRE) to generate the FIRE image.